Down Syndrome (Trisomy 21)

Incidence among live births is about 1/600

Risk increases with increasing maternal age.

Genetics

95% have Trisomy 21 caused by non-disjunction with an ‘extra chr 21’ (so 47,XX,+21 or 47,XY,+21)

Few have de novo translocation of chr21 e.g. t(14;21), but have total 46 chromosomes

Rarely there is mosaicism

The recurrence risk for any woman is 1%; but is higher if there is translocation or in older women

Features at birth include

– Hypotonia

– Short broad hands with Simian crease, clinodactyly

– Wide sandal gap

– Epicanthic folds and upslanting palpebral fissures

– White (Brushfield) spots in the eyes

– Congenital cataract

– Protruding large tongue

– Brachycephaly with a flat occiput and excess neck skin

– GI issues like duodenal atresia, Hirschprung’s disease

– Congenital leukemia or polycythemia

– Cardiac anomalies- ASD, VSD or AVSD

Investigations at birth:

– FISH or Karyotype for confirming diagnosis

– FBC and TSH (newborn blood-spot screening is adequate in UK)

– ECHO to exclude cardiac anomalies

– Newborn hearing screen

Admit to NICU/ SCBU if:

– Cardiac failure or Cyanosis

– Feeding issues, vomiting or delay in passing meconium

– Polycythaemia or Anaemia

– Any other significant clinical concern

Further management:

– Counseling and information about DS

– Signpost to National/ Local DS support group

– Screening investigations (as above) after birth

– Provide DS specific growth chart

– Developmental/ Community clinic follow-up for surveillance of

   – Feeding

   – Growth

   – Developmental support with early intervention teams (Physio, Speech therapy, portage, etc)

   – Hearing

   – Vision

   – Cardiac monitoring (if indicated)

   – Sleep SaO2 trace if symptoms of Obstructive Sleep Apnoea

   – Screening surveillance for Hypothyroidism, Coeliac disease